Steel alloy containing columbium



Patented May 2,1950

STEEL ALLOY CONTAINING COLUMBIUM William H. Norris, Titusville, Pa.,assignor to Allegheny Ludlum Steel Corporation, a. corporation ofPennsylvania N Drawing. Application July 28, 1947, Serial No. 764,245

, '7 Claims.

This invention pertains to the improvement of hot working properties ofchromium-nickel high alloy steels and, more particularly, of thosesteels which have copper and molybdenum additions to impart to themspecial properties. Previous to my invention these steels could beworked only with great difficulty and. great cost and with an extremelypoor recovery. Due to my invention, described hereafter in detail, thesesteels can be produced by ordinary steel mill practice at reasonablecost and with a fair and commercial recovery. This improvement I havebeen able to make by suitable additions of columbium.

Starting, for example, with even a nine inch ingot which may weigh aslittle as 750 pounds, it is, from a practical standpoint, impossible toproduce steels of the type involved by hammer forging and mill rollingmethods to obtain a decent recovery. Corner and face cracking will beprevalent and after grinding out deep defects, the recovery is so smallthat the steel cannot be produced at a reasonable cost figure. If thesesteels are made without proper columbium additions, the recovery may beless than a third, and sometimes even much lower, in which event thecost of production will be substantially doubled. Employing theprinciples of my present invention, a normal recovery of high alloysteel of about twothirds or better of the melted weight can be obtained.

It is an object of my invention to provide a high alloy steel havingimproved hot working properties.

Another object is to provide an improved form of alloy steel havingcolumbium additions.

A further object of my invention has been to provide a less expensiveimproved high alloy steel having a columbium content such that the hotphysical properties obtained by the addition of the main ingredients ofthe alloy are favorably efiected thereby.

These and many other objects of my invention will appear to thoseskilled in the art from the exemplary embodiments thereof, thedescription, and claims.

By this invention, I have been able to produce austenitic steels of sohigh a chromium and nickel content that they, in conjunction with otherelements, produce a particular type of stainless steel which isresistant to a wide range of acids and other chemicals which lowerchromium-nickel steels do not resist at all. These high chromiumnickelsteels are always very difficult to produce, but when they areincorporated with other special elements such as are set forth in myexamples,

they are almost impossible to produce by ordinary steel methods. Theycan now be produced by proper columbium additions as indicated in TablesI and II.

My invention pertains particularly to a chromium-nickel steel having amolybdenum, manganese and copper content, as illustrated by thefollowing exemplary table:

TableI Per cent C (maximum) .15 Mn .50- 2.50 Si .30- 3.75 Cr 17.00-23.00Ni 21.00-25.00 M9 1.50- 5.00 Cu .50- 2.00 S and P, each (maximum) .040-Cb .15- 2.50

Remainder iron The following table is exemplary of two alloy gradeswithin the broader range group previously specified:

Table II Grade A Grade B Per cent Per cent 0 (maximum) Mn Remainder ironFor these two grades, I have shown the preferred range of columbium, asbased on difierent proportionate amounts of silicon and copper. I havefound that a good working percentage of columbium is somewhatintermediate the range or about 1.00% for grade A and about 1.50% forgrade B. That is, Within the critical range 01' columbium, I prefer tooperate substantially between the upper and lower limits (mean) thereof;this has an additional advantage in that it allows for normal plus andminus deviations in melting range practice. Although up to .15% maximumcarbon has been employed, I prefer to use up to about .10% maximum.

The lower columbium limit of the ranges of Tables I and II is theminimum that can be used to produce a noticeable improvement in the hotworking of the steel; and it is desirable to have Mag-M more than theminimum to obtain optimum results. The maximum limit of zcolumbium isdetermined by a number of factors, including a tendency of the columbiumto adversely efiect desired characteristics of the particular alloymetal. I have also determined that hot workability does not increasedirectly in proportion 'to the percentage of columbium and that thepercentage of colu bium is determined by the amount of silicon, copper,and other elements of the alloy. Generally speaking, I prefer to employ3 to 3 /2% molybdenum.

In speaking of a high alloy steel, have refer-- ence to a steel having aminimum chromium content of about 17% and a minimum nickel content ofabout 21%, see the exemplary-tables in column 2 of the specification. Inaccordance with my invention, I have provided a copper-bearing highalloy steel of greatly improved workability which is resistant to a widerange of acids and other chemicals. As indicated by the tables incolumn. 2 the: minimum copper content is about 50%. As previouslyintimated, it will be apparent that the maximum copper content will begoyerne'd'or determined'by the specified columbium range and theproduction of a copper-bearing high alloy steel characterized by itshotworkability.

Although for the purposeof illustrating my invention I have disclosedtwo species of alloys within the broader type of alloy, it will beapparent to those skilled in the art that other species can be-employed,other-elements added and normal impurities and tramp additionsmay bepresent without departing from the spirit and scope of myinvention'asindicated by the appended claims.

What I claim is:

1. A steel alloy containing up to about maximum carbon, about .50- to2.5% manganes .30 to 1.00% silicon, 17.00 to 23.00% chromium, 21.00 to25.00% nickel, 1.50 to 5.00% molybdenum, .50'to 2.00% copper, .50 to1.50% colum'bium,'a'nd the balance substantial-ly' aill iron.

2. A steel alloy containing up to about 15 maximum carbon, about.35033120 2.50% manganese, .30 to.1.00% silicon, 17.00 to. 23.00%chromium, 21.00to 25.00% nickel, 1.50 to 5.00% molybdenum, .50 to. 2.00%copper, up to about 040% maximum each of sulphur and phosphorus, .50 to1.50% columbium, and the balance substantially all iron.

3. A steel alloy containing up to abo ufi".15%. maximumcarbon, about .50to 2.50% manganese, 2.00 to 3.75% silicon, 17.00 to 23.00% chromium,21.00to 25.00% nickel, 1.50 to 5.00% molybdenum, 1.00 t;o'2.00% copper,1.00 to 2.00% columbium, and the remainder iron.

4:. A steel alloy containing up to' about 15% maximum carbon, about .50to 2.50% manganese, 2.00 to 3.75% silicon, 17.00 to 23.00% chromium,21.00 to 25.00% nickel, 1.50 to 5.00% molybdenum, 1.00 to 2.00% copper,up to about 040% maximum each of sulphur and phosphorus, 1.00 to 2.00%columbium, and the remainder iron.

5. steel alloy conta irii'iig about .15% maximum carbon, about 21-to-2=5% nickel, 1-7 to 23% chromium, .50 to 2.00% copper, .50 to 2.50%manganese, .30 to 3.75% silicon, 1.5 to 5% molybdenum, .15 to 2.5%vcolumbium, about 04% maximum' of each of the elements sulfur andphosphorus'and the. balance substantially all iron.

6. An auste'nitic-high alloy stainless steel having about 15 maximumcarbon, about 21 to 25% nickel, 17 to 23% chromium, about .50 to 2.00%copper, .50 to 2.50% manganese, .30 to 3.75 silicon, 1.50 to 5.00%molybdenum, .15 to 2 .50% columbium, the balance substantially all iron;the nickel, chromium, copper, manganese, silicon, molybdenum; col-umbiumand iron all being essential elements, andthe nickel and chromium eachbeing in percentages: such that the percentage of iron predominates thetotal percentage of the. other essential elements of the that thepercentage of iron predominates the total percentage of the otheressential elements of the alloy, the alloy being characterized by it'sim proved' workability andres'is'tance to a wide range of acids andchemicals.

7 H. NORRIS.

REEERENGE S CITED The-following references are of record in the file of;this patent;

UNITED STATES PATENTS Number- Name Date 2,134,670 Parsons Qct. 25, 19382,138,289 i 1938 2,214,128 Q 1940 2,225,730 p 1940 2,447,897 Clarke -1Aug. 24:, 1948

1. A STEEL ALLOY CONTAINING UP TO ABOUT .15% MAXIMUM CARBON, ABOUT .50 TO 2.5% MANAGANESE, .30 TO 1.00% SILICON, 17.00 TO 23.00% CHRONIUM, 21.00 TO 25.00% NICKEL, 1.50 TO 5.00% MOLYBDENUM, .50 TO 2.00% COPPER, .50 TO 1.50% COLUMBIUM, AND THE BALANCE SUBSTANTIALLY ALL IRON. 